The present invention relates generally to methods and devices for detecting the amount of recordable medium remaining in a paper cassette or paper tray that stores a plurality of recordable media (e.g., printing paper, and OHP films). The present invention is suitable, for example, for detecting the amount of remaining sheets of paper in an image-forming device such as a printer, a photocopier, and a facsimile unit.
In recent years, equipment for office automation (or automated clerical works), such as a printer and a photocopier, has been widely used in order to make the office operations more efficient, and in many instances a local area network (LAN) environment is established in the office, where more than one personal computer (PC) shares one printer.
The printer typically includes a printing part, a sheet conveyor mechanism, and a sheet feeder. The printing part prints specified information on a sheet of paper that is timely conveyed from the sheet feeder by the sheet conveyor mechanism. The sheet conveyor mechanism includes a plurality of conveyor rollers such as a pick roller and a register roller, (and other conveyor means, e.g., a conveyor belt, etc.), and conveys a sheet of paper through the printing part, from the sheet feeder to an ejection part. The sheet feeder is comprised of a paper tray and/or a paper cassette that feeds a sheet of paper to the sheet conveyor mechanism. The sheet feeder may take on a manual feeding structure that requires a user to place sheets of paper manually on one-by-one basis, or an automatic feeding structure that enables multiple sheets of paper to be fed automatically on one-by-one basis to the sheet conveyor mechanism, and thus only requires a user to place the sheets on a single occasion.
For instance, the paper cassette is configured to be attachable to and detachable from a printer body, and to accommodate approximately 100-500 sheets of paper, so as to facilitate operations of adding and replacing sheets of paper. When sheets of paper are placed in the paper cassette, a paper placement part on which the sheets of paper are placed pivots about an axis provided at one end of the paper placement part, and thereby the topmost sheet is positioned so that the pick roller as part of the sheet conveyor mechanism may be brought into contact with an end of the sheet opposite the pivoted end so as to dispense the sheet.
The paper placement part may pivot in accordance with a remaining amount of sheets on the paper placement part and always be properly positioned so that the pick roller may dispense the topmost sheet. In order to enable a large amount of paper to be placed for use with a high-speed machine or other performance machines handling a large amount of paper, the paper tray that is configured to have the paper placement part movable vertically may be provided so as to bring the topmost sheet of paper into contact with the sheet conveyor mechanism.
The sheet feeder or printer body is generally equipped with an empty sensor that detects a loss of paper. The printer has a controller that receives information from the empty sensor, and indicates on an operation panel of the printer or a display of a PC (via an operation of a printer driver) that paper has run out. Consequently, a user may know that paper has run out during printing.
However, a user of an image-forming device using a conventional automatic sheet feeder mechanism could not easily and effectively determine whether his/her print command would be complete without suspension due to a loss of paper, when he/she provides the print command.
Since the empty sensor can detect a loss of paper, if paper has run out before printing is initiated, a user may fill paper and then execute a print command. However, if paper remains but the remaining amount is not so much as the number of sheets to be printed, a user does not receive a notification of a loss of paper until the last remaining sheet has been printed. Therefore, a user, for example, who wishes to print a large number of sheets over a lunch break may get aware of a loss of paper after the lunch break, and inefficiently has no other choice but to retry that printing which is suspended halfway from a page that could not be printed.
In order to solve the above problems, several methods for indicating the remaining amount of paper other than the empty sensor have been proposed. For example, one of the methods provides a transparent window in a cassette for visual inspection. However, this method requires a user to stand near a printer, and thus is disadvantageously inconvenient. Particularly, in a LAN environment, where a printer is shared among more than one user, the users usually cannot have the printer near their seats. Moreover, only the visual inspection of a batch of paper disadvantageously cannot provide the accurate number of the paper.
Accordingly, another method has been proposed for detecting the remaining amount of paper using a lever brought into contact with a top surface of paper, so that a transmission-type sensor detects a varied thickness of the butch of paper or an encoder detects an angular variation of the lever. Yet another method has been proposed using a reflection-type sensor or the like to directly detect the remaining amount of paper. These methods would increase complexity of the structure for detecting the remaining amount of paper due to requirement for provision of the lever, or the like, and thus the size and cost of the device would increase. In addition, variation in contact positions of the lever with paper would decrease the reliability of the detection of the remaining amount of paper. Further, these methods would rely only on an actual amount of paper remaining, and thus be unsuitable for use in a LAN environment in particular. To be more specific, supposing that print commands from more than one user who works in a LAN environment are pending in a queue, for example, when three users see a message displayed on their PCs that a current remaining amount of paper in the printer is 70 sheets, and each user gives a print command to print 30 sheets respectively to the printer, each user believes that his/her own print command would successfully be executed, but the last print command would fail to complete due to a loss of paper.
Therefore, it is an exemplified general object of the present invention to provide a novel and useful feeder, image-forming device, and remaining amount detecting method in which the above conventional disadvantages are eliminated.
Another exemplified and more specific object of the present invention is to provide a feeder, image-forming device, and remaining amount detecting method that allows a user to easily and effectively determine whether his/her print command would be complete without suspension due to a loss of paper, when he/she provides the print command.
In order to achieve the above objects, a feeder as one exemplified embodiment of the present invention is a feeder that feeds a recordable medium to a processor part that performs a process, and comprises: a sheet placement part that can accommodate a plurality of the recordable media in a stack of layered sheets, and rotate and shift to a suitable position for feeding the recordable media to the processor part; and a shift amount indicator part that is configured to rotate in a direction of rotation of the sheet placement part as the sheet placement part rotates, so as to enable a shift amount of the sheet placement part corresponding to a remaining amount of the recordable media to be electrically transmitted to an external device. The feeder includes a shift amount indicator part that is configured to rotate in a direction of rotation of the sheet placement part as the sheet placement part rotates, and thus may directly detect the shift amount of the sheet placement part without the need for an additional means such as a lever. The shift amount indicator part electrically transmits the shift amount, and thus serves to have errors reduced compared with a visual inspection, and to ensure high reliability. Electrical transmission of the shift amount allows not only a user near the image-forming device body (e.g., a printer and a facsimile unit) but also users of PCs connected to the image-forming device to keep track of the remaining amount of the recordable media. In other words, the above external device may include the device body having a printing part, and apparatuses connected with the device.
An image-forming device according to the present invention comprises: a feeder including a sheet placement part that can accommodate a plurality of recordable media in a stack of layered sheets, and rotate and shift to a suitable position for feeding the recordable media, and a shift amount indicator part that is configured to rotate in a direction of rotation of the sheet placement part as the sheet placement part rotates, so as to indicate a shift amount of the sheet placement part; a printing part that performs printing onto the recordable media; a sheet conveyor mechanism that conveys the recordable media fed from the sheet placement part in the feeder through the printing part; a detector that detects the shift amount of the sheet placement part indicated by the shift amount indicator part; and a controller that calculates a remaining amount of the recordable media stored in the sheet placement part based upon the shift amount of the sheet placement part detected by the detector. This image-forming device may calculate a remaining amount of recordable media stored in the sheet placement part with a simple structure.
A remaining amount detecting method according to the present invention comprises the steps of: detecting a shift amount of a sheet placement part that is configured to accommodate a plurality of recordable media and to be shiftable according to the number of sheets of the recordable media; calculating a remaining amount of the recordable media stored in the sheet placement part from the shift amount; calculating an amount of the sheets which will remain after a print command is executed by subtracting from the remaining amount the number of sheets which has not been printed yet but is included in the print command; and indicating the amount of the sheets which will remain after a print command is executed in response to the print command. This remaining amount detecting method calculates not only an amount of recordable media which remains at present, but also that which will remain in future (i.e., after print commands are completely executed) in advance, and may thus allow each user to be notified at the time of providing his/her print command whether the print command will successfully be executed. This advantage will be preferred particularly if a plurality of print commands are pending in one printer in a LAN environment. Moreover, this remaining amount detecting method may be embedded in a printer driver and distributed in a CD-ROM or other computer-readable media.
Other objects and further features of the present invention will become readily apparent from the following description of the embodiments with reference to accompanying drawings.